Add the '--trace-version=<1|2>' command line option to select the trace
protocol version requested from the kernel. Requesting version 1 forces
blktrace to use the old BLKTRACESETUP ioctl, while version 2 (the
default) uses BLKTRACESETUP2.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 blktrace.c     | 30 ++++++++++++++++++++++++++++--
 doc/blktrace.8 |  7 +++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/blktrace.c b/blktrace.c
index 72562fdc9d9e..35db26fd4e23 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -283,6 +283,7 @@ static unsigned long long act_mask = ~0U;
 static int kill_running_trace;
 static int stop_watch;
 static int piped_output;
+static int v1;
 
 static char *debugfs_path = "/sys/kernel/debug";
 static char *output_name;
@@ -329,6 +330,10 @@ static int *cl_fds;
 static int (*handle_pfds)(struct tracer *, int, int);
 static int (*handle_list)(struct tracer_devpath_head *, struct list_head *);
 
+enum {
+	OPT_TRACE_VERSION = 256,
+};
+
 #define S_OPTS	"d:a:A:r:o:kw:vVb:n:D:lh:p:sI:"
 static struct option l_opts[] = {
 	{
@@ -433,6 +438,12 @@ static struct option l_opts[] = {
 		.flag = NULL,
 		.val = 's'
 	},
+	{
+		.name = "trace-version",
+		.has_arg = required_argument,
+		.flag = NULL,
+		.val = OPT_TRACE_VERSION
+	},
 	{
 		.name = NULL,
 	}
@@ -455,6 +466,7 @@ static char usage_str[] = "\n\n" \
         "[ -I <devs file>     | --input-devs=<devs file>]\n" \
         "[ -v <version>       | --version]\n" \
         "[ -V <version>       | --version]\n" \
+        "[ --trace-version=<1|2> ]\n" \
 
 	"\t-d Use specified device. May also be given last after options\n" \
 	"\t-r Path to mounted debugfs, defaults to /sys/kernel/debug\n" \
@@ -471,7 +483,8 @@ static char usage_str[] = "\n\n" \
 	"\t-s Make the network client NOT use sendfile() to transfer data\n" \
 	"\t-I Add devices found in <devs file>\n" \
 	"\t-v Print program version info\n" \
-	"\t-V Print program version info\n\n";
+	"\t-V Print program version info\n" \
+	"\t--trace-version Request trace protocol version 1 or 2 from the kernel\n\n";
 
 static void clear_events(struct pollfd *pfd)
 {
@@ -2244,6 +2257,19 @@ static int handle_args(int argc, char *argv[])
 		case 's':
 			net_use_sendfile = 0;
 			break;
+		case OPT_TRACE_VERSION: {
+			int ver = atoi(optarg);
+
+			if (ver == 1)
+				v1 = 1;
+			else if (ver == 2)
+				v1 = 0;
+			else {
+				show_usage(argv[0]);
+				exit(1);
+			}
+			break;
+		}
 		default:
 			show_usage(argv[0]);
 			exit(1);
@@ -2714,7 +2740,7 @@ static int run_tracers(void)
 	if (net_mode == Net_client)
 		printf("blktrace: connecting to %s\n", hostname);
 
-	if (setup_buts2()) {
+	if (v1 || setup_buts2()) {
 		if (setup_buts()) {
 			done = 1;
 			return 1;
diff --git a/doc/blktrace.8 b/doc/blktrace.8
index 820b03aa4c16..c502adcfaa9d 100644
--- a/doc/blktrace.8
+++ b/doc/blktrace.8
@@ -191,6 +191,13 @@ Outputs version
 Sets run time to the number of seconds specified  
 .RE
 
+\-\-trace\-version=\fI1|2\fR
+.RS
+Selects the trace protocol version requested from the kernel. Requesting
+version 1 forces blktrace to use the old \fBBLKTRACESETUP\fR ioctl, while
+version 2 (the default) uses \fBBLKTRACESETUP2\fR.
+.RE
+
 
 .SH FILTER MASKS
 The following masks may be passed with the \fI\-a\fR command line
-- 
2.54.0